diff --git a/net/switchdev/switchdev.c b/net/switchdev/switchdev.c
index df790d3..ebc661d 100644
--- a/net/switchdev/switchdev.c
+++ b/net/switchdev/switchdev.c
@@ -345,6 +345,8 @@
 		return sizeof(struct switchdev_obj_ipv4_fib);
 	case SWITCHDEV_OBJ_ID_PORT_FDB:
 		return sizeof(struct switchdev_obj_port_fdb);
+	case SWITCHDEV_OBJ_ID_PORT_MDB:
+		return sizeof(struct switchdev_obj_port_mdb);
 	default:
 		BUG();
 	}